Crankshaft construction



Sept. 23, 1941. E. v. RIPPINGILLE 2,256,726

CRANKSHAFT CONSTRUCTION 4 Filed Aug. 24, 1939 t :inventor Patented Sept.23, 1941 2,256,726` cnANxsnAFT CONSTRUCTION Edward V. Rippingille,Detroit, Mich., assignor to General Motors Corporation, Detroit, Mich.,a corporation of Delaware Application August 24, 1239, serial No.291,723

` 3Clalms.

' This invention relates to crankshaftsbuilt 11D of a number o fseparate parts. k v

'Ihe object of the invention is a crankshaft with vhollow crankpins andmain journals, built up of similar separate parts which are relativelysimple and cheap to make.

A further object of the invention is a. builtl up crankshaft with hollowmain journal and crankpin portions, and crank cheeks of ideal shape,contour and section, for maximum strength with minimum weight.` I

The above and other objects of the invention will be apparent as thedescription proceeds.

According to the invention, the separate parts each comprise half alcrank throw, including a single crank cheek having cupped bosses onopposite sides thereof constituting approximately half a main journaland half a crankpin portion respectively.

The separateparts may be cast or formed in any suitable way, but are`preferably forgings. They can be forged in a simp1 esmall andinexpensive die, in a plane at right angles to the crankshaft axis, withthe crank cheek,y main journal andy crankpin portionscupped or hol- (cl.'I4-597) pressions 26 and 2l and constitute half of a hollowed out mainjournal, and half of a hollowed y out crankpin respectively. The crankcheek 20 .is forged with a rimmed crescent shaped depression 29 onthe'side opposite to the crankpin portion 25, for maximum strength withlightness.

The half crank throws such as I 0 are welded together, crankpin portionto crankpin portion, as'shown for example 'at 30 in Fig. 1, to form acomplete throw;.if as in Figs. 1 and 2, there is more than one throw,successive throws 'are crankshaft, are completed, and any desiredextension of the ends of the crankshaft is provided,

by welding pieces such as 40 and 4I respectively thereto.

The construction in Fig. 4 is essentially similar to that of Figs. 1, 2and 3, but whereas the cupped out depressions 26 and 2l in the mainjournal and crankpin portions of each half crank lowed out to-anydesired extent, in a direction parallel to the crankshaft axis.

Two such separate parts comprising half a crank throw may have theircrankpin .portions joined together toform a single throw crank- ,crankthrow, of which the crankshaft of Fig. 1

is constructed.

Fig. 4 is a sectional view of a part of a crank shaft having a shorterthrow than that of Figs. 1,`2 and 3.

The crankshaft of Figs. 1 and 2'has four'main bearings I, 2, 3 and 4,-and three crankpins B,

throw such as Iii do not overlap in Figs. 1, 2 and 3, the throw isshorter in Fig. 4 and the cupped out depressions 46 and 41 in the mainjournal and crankpin portions 48 and 49 of the half crank throw 50 dooverlap.

It will be appreciated that a built -up crankshaft of the kindillustrated makes it possible to obtain hollow pins and journals to anextent otherwise impossible, and actually to improve the shape, contourand section of the crank cheeks, instead of weakening them as would bethe case in boring a shaft forged in the conventional manner, for thereason that the crankpins and main journals cannot be bored except witha bore exl and 1, at 120 to each-other. Itis built up' of six identicalforgings III, Ii, I2, I3, Il and I5 respectively, each comprising halfav crank throw.

As shown most clearly in Fig. 3, each half crank throw such as I0includes a single crank cheek 2li, with bosses 2l and 25 on oppositesides thereof. The bosses I4 and I5-have cupped detending through thecrank cheeks, and it would be impossible to do this in a solid forgedcrankshaft having the external proportions of Fig. 4 for instance. f

I claim: l 1. A crankshaft built up of similar separate integral parts,each comprising half a crank throw including a single imperforated crankcheek having cupped bosses on opposite sides thereof,fcon

stituting halves of hollowed out main journal and crankpin portionsrespectively.

2. A crankshaft according in claim l, in which .the cupped bossesoverlap and have overlapping depressions therein.

3. A crankshaft according to claim 1, in which y each of the crankcheeks has a rimmed, crescent EDWARD Y. RIPPINGILLE.

